An M-249 SAW...I shot about 7 drums through it (200 rounds per drum) of blank ammo during a Field Training Exercise (Ulchi Focus Lense in Korea), and worked fine, I kept pouring CLP in the action, and it finally failed me on that 7th drum (Of course military blanks are SERIOUSLY dirty!). I have had several M16A2s fail on me through no fault of my own cleaning, and an M4. Other than that, I meticulously clean my Personally Owned Weapons, except for my shotguns, and .22s, which get it once every six months, once a month during bird season on my shotguns.